1. Field of the Invention
This invention relates to the field of radio receiver and transmitter calibration and testing equipment and, more particularly, to an apparatus and method suitable for the testing of police band radar detectors capable of detecting microwave transmitters of the type used for automobile speed measurement.
2. Description of the Prior Art
There is no known reliable performance verification method or apparatus practical for testing a police radar detecting device. In order to provide background information so that the invention may be completely understood and appreciated in its proper context, reference is made to the following prior art publications:
Article in Car Audio vol. 4 no. 3, pages 92-103, March 1991, entitled "Eight Triband Radar Detectors"; Article in Radio Electronics vol. 61 no. 2, pages 37-38, February 1990, entitled "Radar Detector Tester"; Owner's Manual, Passport radar receiver, copyright 1989 by Cincinnati Microwave, Inc., pages 32-33; Owner's Manual, Bel Vector radar detector, Bel-Tronics Ltd. (copyright unknown); Article in Radio Electronics vol. 57 no. 8, pages 39-42, 85, August 1986, entitled "Radar Speed-Gun Controller"; Article in Radio Electronics vol. 57 no. 7, pages 52, 97, July 1986, entitled "Radar Signal Detector."
The article cited in Car Audio Magazine evaluates the performance of several radar detectors on the X, K, and Ka bands utilizing police speed measurement equipment. This cited method is clearly impractical and prohibitively expensive for routine testing of radar detectors. The article states that radar detector malfunction is not an unusual occurrence illustrating the need for a reliable method and apparatus to verify radar detector performance.
The article cited in Radio Electronics for February 1990 discloses a method and apparatus to compare radar receiving sensitivity between two radar detectors. However, that method and apparatus is used to determine a relative sensitivity. Furthermore, it is believed due to signal strength the operator must leave the automobile in order to effect a change in the field strength meter of the radar detector thus performance verification may not be implemented while the radar detector is in use. It is also believed that the cited apparatus would transmit at power levels against regulatory policy.
Another disclosure which furnishes background information is the above cited Owner's Manual for Passport radar receiver. The method includes an averaging technique of false signals. However, that method requires the presence of routinely encountered false signals on a regular route and is claimed to be a semi-reliable method by this reference. Additionally, the cited method will not test the performance of signals used exclusively for police band radar.
The article cited in Radio Electronics for August 1986 discloses an apparatus for testing and calibrating radar equipment in the laboratory. The disclosed speed-gun controller interferes with police radar and is therefore illegal.
The article cited in Radio Electronics for July 1986 discloses an apparatus to test a radar signal detector by the generation of a non-specific broadband radio frequency signal. An RF signal, such as that derived from the cited apparatus, is believed to be against regulatory policy.
The final reference cited from Bel Vector Owner's Manual discloses an admittedly imprecise method that includes the use of false signals as a performance indicator.
The invention which we describe herein is usable by individuals untrained in the field of electronics for the purpose of performing simple, rapid and accurate tests to determine whether radar detection equipment is functioning. The current method verifies radar detector performance using one radar detector. The method utilizes an apparatus with minimal power output necessary to accomplish the task and can be applied while the radar detector is in use. The current method includes a the proximity measurement, where proximity of radar detector to apparatus varies field strength. This measurement is used as a standard in subsequent tests for precise verification of performance. The current apparatus transmits at three different frequencies thereby testing all police radar band reception of the radar detector.